1. Field of the Invention
This invention relates to a light-emitting device, more particularly to a light-emitting device including a waveguide structure having a plurality of nanorods formed on a n-type semiconductor layer.
2. Description of the Related Art
It is known in the art that light extraction efficiency of a light-emitting diode is considerably limited due to the laminated layered structure of the light-emitting diode, which can cause total internal reflection of light generated from an active layer of the light-emitting diode, which, in turn, can result in a decrease in the light extraction efficiency. Conventional methods for enhancing light extraction efficiency normally involve increasing surface roughness of the laminated layered structure of the light-emitting diode so as to reduce total internal reflection of light in the light-emitting diode. However, in UV, blue, or green light emitting diodes, since the p-cladding layer thereof is relatively thin, which has a layer thickness required to be not greater than 200 nm, surface roughening of the same tends to cause short-circuiting of the light emitting diode and has an adverse effect on the electrical properties of the light emitting diode. U.S. Pat. No. 7,132,677 discloses a light emitting device including a plurality of nanorods, each of which has a n-cladding layer, an active layer formed on the n-cladding layer, and a p-cladding layer formed on the active layer. Although the light-emitting diode thus formed can enhance the light extraction efficiency, manufacturing of the same is complex and expensive.